The present invention generally relates to damper systems used to control air flow in heating and cooling forced-air ventilation systems. More specifically, the present invention relates to damper systems of an open circular cross-section that employs an iris shutter type construction to restrict air flow through the open circular cross-section.
Damper systems that employ an iris shutter type construction for air flow restriction are generally referred to as iris dampers. Iris dampers are inserted into the duct work of forced-air ventilation systems. Iris dampers 10 include an open circular cross-section 12, which allows the flow of the force air through the damper, as shown in FIG. 1. Iris dampers 10 also include a plurality of iris blades 14 which are stored in the casing 16 of the damper 10, as shown in FIG. 1. When air flow is to be restricted by the damper, the iris blades 14 rotate into the open circular cross-section 12, similar to the action of an iris shutter of a camera.
When set in the fully closed position, current large iris dampers for use in commercial applications still have an opening in the middle, through which air continues to flow. These iris dampers have been used for controlling the rate of air flow, but do not stop the air flow entirely. The iris blades do not form a perfect circle when closed, due to the sectional nature of the iris blades. Many commercial air flow applications, such as heath care isolation suites and research laboratories, require the damper to modulate from one hundred percent open to one hundred percent closed. In these commercial applications, the ability to measure air flow during modulation is commonly required. Most ventilation systems do not have the room for the installation of separate air flow measuring equipment. Standard pitot tubes are sometimes utilized in the center of the open circular cross-section to measure air flow. Current iris dampers do not provide a positive damper seal in the closed position about the pitot tube, due to their inability to close in a perfect circle about an object. To obtain a no flow condition some other type of closure device must be positioned upstream or downstream of the current iris damper. This adds to the complexity of the damper system installation. These type of installations also do not provide an accurate air flow signal during modulation of the closure device or iris blades. Another problem with the use of current pitot tubes is that they employ small diameter sensing ports that become plugged with dirt commonly found in ventilation air before the air is filtered.
It is an object of the present invention to provide an apparatus and means of sealing off the open circular cross-section of an iris damper when the iris blades are their closed position.
It is an object of the present invention to provide a total pressure device as part of the iris damper which over comes the problems associated with current pitot tubes.
A damper system with a sealing plug, which incorporates an air flow monitoring system. The damper system utilizes current designs of the iris damper and incorporates a sealing plug positioned in the open circular cross-section of the iris damper. One version of the sealing plug incorporates a sealing groove in the sealing plug, while another version employs different types of sealing gaskets. The sealing groove and sealing gaskets provide a positive seal about the sealing plug when the iris blades are in the closed position. An additional feature that can be incorporated into the sealing plug is an air flow monitoring system. The sealing plug can include a chamber where total pressure of the air flow passing the sealing plug can be measured.